Synergistic Effect of Bifidobacterium Pseudocatenulatum and Fructooligosaccharides Against Escherichia Coli

Abstract

8 wild type strains of Bifidobacterium pseudocatenulatum and 4 commercial strains
(B. pseudocatenulatum JCM 1200, B. infantis ATCC 15698, B. breve ATCC 26720
and B. longum BB536) were screened for inulinase activity on modified PY-0 and
PY-I agar. Wild type B. pseudocatenulatum F117 and reference B.
pseudocatenulatum JCM 1200 were determined to have the highest inulinase
activity. This activity was apparently higher on PY-0 agar in comparison to PY-I
agar. In batch cultivation, growth of B. pseudocatenulatum F 1 17 was enhanced in
PY-0 medium (0.38 h-' and 2.64 x lo8 cfulrnL), compared to PY-G (0.48 h-' and
5.45 x lo8 cfulrnL) and PY-I medium (0.20 h" and 1.70 x lo8 cfulmL) from the
respective, initial specific growth rate and maximum growth. Acetic, lactic and
formic acid production was also found to be relatively higher in PY-0 medium
(38.60 mM; 37.48 mM; 7.37 mM) compared to PY-G medium (11.95 mM; 22.77
mM; 5.91 mM) or PY-I medium (12.34 mM; 19.73 mM; 0 mM). In therapeutic study, the antagonistic effect against E. coli V157 by B. pseudocatenulatum F117
was contributed by pH lowering of the growth medium. This effect was especially
intensified at pH below 5.0. Antagonistic effect found in PY-0 medium was greater
compared to that of PY-G medium. The kinetics of antagonistic effect could be
divided into two apparent phases. It was the condition before (first phase) and after
(second phase) B. pseudocatenulatum F117 to achieve the maximum growth (lo9
cfu/mL), with relatively intense antagonistic effect at second phase. Organic acid
was highly produced at second phase (PY-G medium: 45.5728.99 mM; PY-0
medium: 61.542 1 1.92 mM) rather than first phase (PY-G medium: 25.59k3.16; PY-
0 medium: 30.46k7.21 rnM) implicative of the importance of probiotic
concentration for effective antagonism. Oligohctose was found to be able to
stimulate the growth of B. pseudocatenulatum F117 and consequently shorten the
time for the maximum growth to achieve, from 18 hr in PY-G medium to 12 hr in
PY-0 medium. Besides, lactic acid production was initiated 6 hr earlier in PY-0
medium than to PY-G medium, which could be an added inhibitory advantage. With
low bifidobacteria dose (10' cfu/mL), the antagonistic effect displayed was quite
identical to a higher dose (lo8 cWmL) employed. B. pseudocatenulatum F1l7 was
found to obtain the maximum growth in 18 hr for the both trial doses in either
growth medium. In prophylactic study, PY-0 medium could not be observed to
further enhance the antagonistic effect in PY-G medium. E. coli V157 (1 o8 cfu/mL)
was unable to sustain and multiply to a higher population but decreased in numbers
in either growth mediums. Finally, a higher oligofructose concentration (1.0 %) was
shown to dramatically improve the antagonistic effect as compared to the lower concentration (0.5 %) used, in both therapeutic and prophylactic study. This effect
was again due to an even higher amount of organic acids produced.